This invention relates to an automatic weighing apparatus and, more particularly, to improvements in a hopper in an automatic weighing apparatus suitable for weighing frozen foods.
An automatic weighing apparatus, now in practical use, operates by supplying articles to a plurality of weighing machines, computing combinations of weight values obtained from the weighing machines, selecting a combination of the weight values having a total weight equal to or closest to a predetermined fixed weight, and discharging only the articles contained in the weighing machines corresponding to the selected combination (referred to as the "optimum combination"), to obtain a batch of the articles having a weight equal or closest to the fixed weight.
In the automatic weighing apparatus of the type described, each of a plurality of weighing machines is equipped with a weighing hopper for accommodating a batch of articles therein, and with a pool hopper disposed above the weighing hopper, for quickly supplying the weighing hopper, with the next batch of articles to be weighed when the previously weighed batch of articles has been discharged from the weighing hopper.
As shown in FIG. 1, each of these hoppers has a hopper body a the lower end portion of which is provided with a discharge port a' from which articles are discharged. Each hopper further includes an openable and closable gate b provided at the discharge port a', a toggle-type link mechanism c actuatable under the control of an external force for opening and closing the gate b, which is also operable to lock the gate shut when the gate is closed, and a spring d which acts through the link mechanism c to bias the gate b in the closing direction.
The foregoing arrangement is beset by a number of problems where the articles being weighed are frozen foods, or where the automatic weighing apparatus is employed in a freezer chamber. Specifically, since the hoppers are chilled when the weighing apparatus finds use in the manner described, water contained in the frozen food or in the air itself in the form of moisture freezes on the hoppers to produce an icy deposit. When such a deposit forms, particularly at the discharge port a' of a hopper, as indicated at e in FIG. 1, the gate b contacts the deposit and is no longer capable of closing off the discharge port a'. As a result, articles introduced into the hopper will leak from the gap between the hopper body a and the gate b. Furthermore, with the gate b being unable to completely close the discharge port a', the link mechanism c is incapable of bringing the gate b to the home position, which is necessary to lock the gate in the closed state. Under such condition, moreover, only a small component of the biasing force applied by the spring d in the closing direction is capable of acting upon the gate b through the link mechanism c. For these reasons, the gate b tends to open naturally under the weight of the articles contained in the hopper body a, thereby contributing to leakage of the articles in the manner described above.